That figure is up two points on a month ago – compared with 43 per cent who thought the decision was right – down three points. YouGov questioned 1,590 adults on April 25 and 26.

The UK makes a net contribution to the EU of around £199 million a week, according to the latest official estimates.

The figure for 2015 is included in the breakdown of the UK’s current account, known as the Pink Book, published by the Office for National Statistics (ONS).

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The Leave campaign attracted criticism during the EU referendum for printing a slogan on the side of its battlebus that said: ‘We send the EU £350 million a week.’

Supporters of the Remain campaign said the figure was misleading as it did not take into account the money the UK receives from the EU in the form of a rebate, as well as payments made to the public sector.

Boris Johnson stood by the £350 million figure on Thursday when interviewed on ITV’s Good Morning Britain, saying it was ‘not disputed’.

The ONS figures for 2015 suggest the UK’s gross contribution to the EU, before the application of the rebate, totalled £19.6 billion – or about £376 million a week.

But, as the UK Statistics Authority pointed out during the referendum campaign, the Treasury pays the UK’s contributions to the EU after deducting the value of the rebate.

Gina Miller said her campaign is to stop Hard Brexit (Picture: AFP/Getty Images)

The rebate in 2015 was £4.9 billion. Subtracting this from the gross contribution gives a figure of £14.7 billion.

A further subtraction of the EU’s payments to the UK public sector gives the final figure of £10.4 billion, or about £199 million a week.

The precise amount of money the UK sends to the EU is difficult to calculate.

According to a study published by the ONS in May 2016: ‘None of the figures on the money flowing between the UK and EU are fully reflective of the total costs and benefits of EU membership as these are complex and difficult to quantify.’

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For example, European Union payments made directly to the private sector – such as universities and research organisations – are not included in these figures, as the ONS looks only at transactions directly between the EU and UK public bodies.

The breakdown for 2016 is due to be published later this year.

The figures were released as Gina Miller, who launched a legal challenge against Brexit, started a campaign of tactical voting to prevent a hard Brexit.

(Picture: Getty)

The idea has been backed by almost 10,000 people and raised £300,000 which will be used to locally support candidates from any party committed to keeping the UK’s Brexit options open.

She insisted it was a non-party political movement that wanted the best outcome for Britain and a range of voices in Parliament.

‘If we have, at the end of the day, if you like, an elected dictatorship, then that’s not democracy,’ she said.

‘Whilst Brexit is a very important issue in this election, there is a much wider issue here which is about electing MPs who will stand on their principles and hold the government to account.’

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In other Brexit news, Boris Johnson has insisted he stands by his controversial claim that Britain sends £350 million a week to the European Union that could otherwise be spent on the NHS.

The claim – emblazoned on the side of Mr Johnson’s battlebus during last year’s EU referendum campaign – was denounced by the official statistician as ‘misleading’ and has since been disowned by senior members of the Brexit campaign.

Challenged over whether he stood by the £350 million claim, Mr Johnson told ITV1’s Good Morning Britain: ‘Of course I do,’ and insisted the figure was ‘not disputed’.

He described the sum as ‘£350 million a week which we do not currently control which could be spent on our priorities, including the NHS’.

During the referendum campaign, the chairman of the UK Statistics Authority, Sir Andrew Dilnot, took the unusual step of saying he was ‘disappointed’ that the Leave campaign persisted with the £350 million figure after being warned it was ‘misleading’. Sir Andrew said the way the campaigners were deploying the figure risked undermining trust in official statistics.

The figure does not take account of the UK’s rebate, secured by Margaret Thatcher, or the cash returned to Britain by the EU.

Immediately after the Leave victory, then Ukip leader Nigel Farage admitted the figure was a ‘mistake’ and said he would not have made the claim.

But Mr Johnson told Good Morning Britain: ‘As far as I remember, the gentleman in question belonged to another party and wasn’t on my bus.’